Thermal and acoustic insulation fabric

ABSTRACT

An insulating fabric which substantially prevents propagation of fire uses a blend of modified aluminum oxide-silica fibers and organic fibers in a multi-layer blanket.

[0001] This application claims priority to U.S. provisional applicationNo. 60/306,164, filed Jul. 19, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a nonwoven fabric suited for use as aninsulating layer, such as a thermal and acoustic insulating layer in anaircraft fuselage.

[0004] 2. Description of the Related Art

[0005] Blankets providing thermal and/or acoustic insulation are used inaircraft and other vehicles to protect passengers from exteriorenvironmental temperature extremes and to dampen engine noise.

[0006] As described in U.S. Pat. No. 5,169,700 (“Faced Fiber GlassInsulation”) and U.S. Pat. No. 5,108,821 (“Self-Extinguishing BlanketEnclosed With Plastic Films”), both incorporated herein by reference,prior art insulation blankets typically comprise a batting of a fibrousmaterial such as fiberglass, and a film covering which serves to resistthe uptake of moisture by the batting material.

[0007] Among the drawbacks of the prior art insulation blankets is that,depending on the materials of construction, the blankets may contributeto the propagation of a fire by providing a pathway into the cabin ofthe aircraft. Metallized polyethylene terephthalate (PET) films found onsuch fabric, for example, have been known to propagate fire.

[0008] U.S. Pat. No. 5,624,726 and U.S. Pat. No. 5,759,659, hereinincorporated by reference, describe an insulation blanket comprising alofty batting of thermoplastic fibers and a high temperature resistantlayer of ceramic oxide fibers, encased within a heat-sealable, flameretardant, rubber-toughened thermoplastic polyolefin polymer. While someof these fabrics may be effective in preventing burn-through, theireffectiveness in preventing the propagation of fire when exposed to aflame under a radiant heat source is dependant on the durability of thethin ceramic layer.

[0009] U.S. Pat. No. 5,904,318, herein incorporated by reference,discloses a reinforced skin structure containing insulation comprisingheat-stabilized, oxidized polyacrylonitrile (PAN) fibers. While PANfibers work well in preventing burn-through of fire into an aircraftcabin interior, oxidized PAN fiber may alter the pH of condensatecontacting it, resulting in accelerated corrosion of the skin of theaircraft. Moreover, toxic gases including cyanogen, carbon monoxide, andnitrogen oxide are possible byproducts of a fire involvingnitrogen-containing synthetics such as oxidized PAN.

[0010] Insulation blankets made of commodity inorganic fibers such asfiberglass are irritating to the touch and difficult to process ontextile equipment. The fibers fracture easily in the process ofmanufacturing the blanket assembly, during installation, or wheneverthey are handled.

[0011] Commercially available insulation materials which containfiberglass, glass wool, and other inorganic fibers also typically causeirritation of the skin, eyes, nose, and mouth.

[0012] In addition to causing irritation of the skin, there is a healthrisk associated with glass fibers when broken fragments become airborne.Glass fibers have a propensity to fracture and create dust due to theirbrittle nature. These fiber fines, when inhaled, pose a serious risk tohuman health because they are capable of entering the lungs, leading toa chronic condition known as silicosis. For example, a rotary glassfiber commonly used in aircraft insulation has a mean fiber diameter of4.7 microns and a standard deviation of 2.0 microns. As fibers having adiameter below 3 microns are within the respirable range, a significantportion of these fiber fines is within the respirable range.

[0013] Aircraft using conventional insulation blankets accumulate, andfrequently fly with, more than a ton of moisture vapor condensate withinsaturated, soggy, matted and collapsed blankets.

[0014] Thus, there has been a long felt need in the industry for animproved insulation material; one which offers improved resistance tofire propagation while overcoming the abovementioned limitations of theprior art.

SUMMARY OF THE INVENTION

[0015] An object of the present invention is to provide thermal andacoustic protection with a novel fabric that will not contribute to thepropagation of a fire. Preferred fabrics according to the invention passnew proposed changes to the Federal Aviation Administration's radiantpanel test described in 14 C.F.R., Appendix F to Part 25 thereof. Thesechanges to the rule are described in a Notice of Proposed Rulemakingpublished in the Federal Register at Vol. 65, No. 183 (Sep. 20, 2000),pages 56992-57022, herein incorporated by reference.

[0016] Another object of the invention is to provide an insulationfabric that repels water, and thereby prevents the insulation frombecoming saturated with large quantities of condensate, improving thecorrosion resistance of the aircraft skin, as well as improving fuelefficiency and payload capacity of an aircraft.

[0017] A further object of the invention is to provide an insulationthat is soft, non-abrasive, and pleasant to the touch, and which isreadily processed on standard textile manufacturing equipment.

[0018] A further object of the invention is to provide an insulatingmaterial having fiber diameters large enough so that particles formedfrom the insulation are safely above the respirable range of 3 micronsor less.

[0019] These and other objects are achieved by a fireblocking insulationmaterial which comprises at least a first nonwoven batt having modifiedaluminum oxide-silica fibers present in an amount between about 1.0percent by weight and 95.0 percent by weight and organic fibers presentin an amount between about 5.0 percent by weight and about 99.0 percentby weight. The preferred aluminum oxide-silica fibers are modified by anextraction with acid, as described in WO 98/51631, herein incorporatedby reference.

[0020] In preferred embodiments, the insulation material comprises aplurality of layers including at least one nonwoven batting layer havinga mixture of the modified aluminum oxide-silica fibers, organic fibers,and at least one further nonwoven batting layer consisting essentiallyof organic fibers.

[0021] The organic fibers used may be any commonly used in the art,although meta-aramid fibers, para-aramid fibers and mixtures thereof arepreferred for many fireblocking applications.

[0022] In preferred embodiments, a water repellent coating is applied tothe insulation material and cured. In other preferred embodiments, theinsulation material comprises an acoustic dampening layer between layersof batting material, and a facing layer to resist the uptake of moistureby the batting layers. The material may also comprise a scrim asstructural support.

[0023] Although this invention is particularly described in connectionwith aircraft applications, it is also suited for many otherapplications including, without limitation, insulating fabric in othertransportation vehicles such as race cars, automobiles, trains, andbuses; insulating fabric in spacecraft such as the space shuttle orrockets; protective clothing applications including firefighters'turnout coats and other gear; protective suits worn by racecar drivers,astronauts, and the like; protective garments such as gloves, aprons,and gaiters worn in welding applications or the metal-working industry;ingot moulds; survival suits worn by mariners or military rescuepersonnel; insulating bedding material; sleeping bags; filtrationfabrics, including those used in the electrical power generatingindustry; pipe insulation; high-pressure steam line insulation; doorseals for furnaces, ovens, broilers, boilers; fire and heat-sourceprotection for firefighters' and other hoses; and thermal protection ofelectrical wires/cables.

[0024] Further objects and advantages of this invention will becomeapparent from a consideration of the drawings and the followingdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a cross sectional view of an insulation fabric inaccordance with the invention.

[0026]FIG. 2 and FIG. 3 are graphs of test results of FAA radiant paneltests conducted on insulating fabrics according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring to FIG. 1, the insulating fabric (30) contains at leastone lofty nonwoven batt (10) consisting of a blend of at least one typeof organic fiber and a high performance inorganic fiber. Any number ofadditional batts (12), (14), (16) may be mechanically needled to orotherwise entangled with the fibers of the first batt to produce aninsulating fabric of multiple layers. The additional batts containorganic fibers or a combination of organic and inorganic fibers.

[0028] In preferred embodiments of the invention, the inorganic fiber isa modified aluminum oxide silica fiber comprising at least 1% by weightof the nonwoven fabric layer(s) containing it. Most preferred is a highperformance silica fiber commercially available as belCoTex® frombelChem Fibers GmbH of Germany.

[0029] The standard version of belCoTex® is an acid-extractedAl₂O₃-modified (aluminum oxide-modified) silicic acid derived staplefiber pre-yarn. In the standard form, the glassy characteristic natureof the fiber has been completely overcome by an acid extraction step.This fiber provides long-term temperature resistance at 1000° C., yetpossesses a soft, fleecy, voluminous character that makes it bothpleasant to the touch and easily processable on textile equipment. Themodified SiO₂ (silica) network of belCoTex® allows for OH (hydroxyl)groups and H₂O (water) molecules to become incorporated. Thiscontributes to the softness of the fiber, its pleasant hand, and theease with which it is processed on textile equipment. The mean fiberdiameter of belCoTex® is 9.2 microns and the standard deviation is 0.4microns; as a result it does not carry the health risks associated withglass fibers having fiber diameter distributions that extend into therespirable range. Preferred fibers for use with the invention aredescribed in WO 98/51631, herein incorporated by reference. Particularlypreferred is an acid-extracted silica-based fiber having about 70-75weight percent Si0 ₂, about 15-25 weight percent Na₂O (or K₂O), andabout 1-5 weight percent of Al₂O₃.

[0030] Preferred embodiments contain blends of 5-95% inorganic modifiedaluminum oxide fibers such as belCoTex® and 5-95% organic staple fibersas described above. The most preferred embodiments of this inventioncontain 15-50% belCoTex® aluminum oxide-modified silica fibers.

[0031] An acoustic dampening layer (18) may be incorporated into theinsulating fabric positioned between multiple batts or on an exteriorface of the fabric. The dampening layer may be adhered to the fabric bymeans such as adhesive glue, or by alternative methods. For example, thedampening layer may be directly cast onto the fibers, it may bemechanically attached, i.e., by needling or stitching, or it may bethermally bonded. Multiple dampening layers may be used if desired.

[0032] A supporting scrim (20) may be incorporated into the insulatingfabric. If used, the scrim may be positioned either on an exterior face,between layers, or any combination thereof. The insulating fabric maycontain no scrim, one, or multiple scrims. The scrim is generally aloosely woven fabric (without limitation, typically on the order of 5-20picks per inch in the warp and weft directions) providing structuralintegrity to the finished insulation.

[0033] A film or facing layer (22) may be incorporated into theinsulating fabric. The facing layer serves to improve the soundtransmission loss of the insulating fabric and also allows for theinsulating fabric to be easily cleaned by wiping it with a cloth. Thefacing layer is preferably made from poly(vinylfluoride) (PVF),poly(etheretherketone) (PEEK), or polyimide film such as Kapton®available from DuPont, but may be made from other materials including,without limitation, fire retardant polyolefin films, polyimide films,and other films known to those in the art. Glass or other fibers may beincorporated into such films for additional strength and support. Thefacing layer may cover one or more sides of the insulating fabric, ormay completely enclose it for additional protection. An insulatingfabric enclosed with such a film will be further protected against watervapor condensation.

[0034] In preferred embodiments of the invention the organic fibers usedin all of the layers are organic staple fibers of poly m-phenyleneisophthalamide, poly p-phenylene terephthalamide, commonly referred toas meta-aramid and para-aramid fibers respectively or blends thereof.Alternatively, other organic fibers may be used, including withoutlimitation, blends of melamine, polyimide, polybenzimidazole (PBI),polyphenylenebenzobizoxazole (PBO), carbon, polyphenylene sulfide (PPSor sulfar), poly etheretherketone (PEEK), novoloid (Kynol®), saran,polytetrafluoroethylene (PTFE, fluorocarbon), polyamide imide (Kermel®),modacrylics, vinal, Visil®, wool, or treated cotton fibers.

[0035] The felt batts of the insulating fabric are also furtherprocessed to impart a hydrophobic character to the fibers for waterrepellency. A fluoropolymer treatment, silicone coating, or other meansmay be used to impart water repellency.

[0036] Finished fabrics according to the invention are operable over awide range of thicknesses and weights per unit area. Generally, fabricsaccording to the invention have a weight range between 2.0 and 100.0oz/yd². The weight in some instances will be dictated by theapplication, so that a wearable fire-protective suit might use fabrichaving a weight in the 2.0 to 10.0 oz/yd² range, while an insulationmaterial in the foundry industry might range between 50.0 oz/yd² to100.0 oz/yd² or higher. Preferred fabrics in the aviation industrytypically range between about 20.0 oz/yd² and about 50.0 oz/yd². Thethickness of fabrics according to the invention typically ranges betweenabout 0.05 and about 2.0 inches. Preferred fabrics for use in aircraftgenerally have a thickness between about 0.10 and about 2.0 inches, morepreferably between about 0.5 and about 2.0 inches.

EXAMPLES

[0037] The following examples were produced (or designed) using severalfiber blends. All percentages are in terms of total fiber weightpercent, unless otherwise noted. These examples, actual or prophetic,are not to be deemed limiting of the invention.

[0038] A first fiber blend A was prepared according to the followingformula: 100% poly (m-phenylene isophthalamide) staple fiber, 5.5denier×3 inches in length. It will be understood that a “blend,” as usedherein is a term of art which can refer to a nonwoven batt consisting ofone type of organic fiber

[0039] A second fiber blend B was prepared according to the formula: 85%poly (m-phenylene isophthalamide) staple fiber, 1.5 denier×1.5 inches inlength; and 15% poly (m-phenylene isophthalamide) staple fiber, 2denier×3 inches in length.

[0040] A third fiber blend C was prepared according to the formula: 95%poly (m-phenylene isophthalamide) staple fiber, 5.5 denier×3 inches; and5% belCoTex® fiber, average fiber diameter of 9 micrometers×2.5 inches.

[0041] A fourth fiber blend D was prepared according to the formula: 90%poly (m-phenylene isophthalamide) staple fiber, 5.5 denier×3 inches; and10% belCoTex® fiber, average fiber diameter of 9 micrometers×2.5 inches.

[0042] A fifth fiber blend E was prepared according to the formula: 85%poly (m-phenylene isophthalamide) staple fiber, 5.5 denier×3 inches; and15% belCoTex® fiber, average fiber diameter of 9 micrometers×2.5 inches.

[0043] A sixth fiber blend F was prepared according to the formula: 80%poly (m-phenylene isophthalamide) staple fiber, 5.5 denier×3 inches; and20% belCoTex® fiber, average fiber diameter of 9 micrometers×2.5 inches.

[0044] A seventh fiber blend G is prepared according to the formula: 50%poly (m-phenylene isophthalamide) staple fiber, 5.5 denier×3 inches; and50% belCoTex® fiber, average fiber diameter of 9 micrometers×2.5 inches.

[0045] An eighth fiber blend H is prepared according to the formula: 90%belCoTex® fiber, average fiber diameter of 9 micrometers×2.5 inches, and10% poly (p-phenylene terephthalamide) staple fiber, 1.5 denier×2.36inches in length.

[0046] A ninth fiber blend I is prepared according to the formula: 50%poly (m-phenylene isophthalamide) staple fiber, 5.5 denier×3 inches inlength, 25% polybenzimidazole staple fiber, 1.5 denier×3 inches inlength, 25% belCoTex® fiber, average fiber diameter of 9 micrometers×2.5inches.

[0047] The foregoing blends A-I are tabulated on Table 1 below: TABLE 1Meta- Para- aramid¹ aramid² belCoTex⁵ Blend (wt %) (wt %) (wt %) PBI A100  0  0 0 B 85⁴, 15³ 0  0 0 C 95 0  5 0 D 90 0 10 0 E 85 0 15 0 F 80 020 0 G 50 0 50 0 H  0 10  90 0 I 50 0 25 25 

[0048]¹/ 5.5 denier×3 inches, except as otherwise noted

[0049]²/ 1.5 denier×2.36 inches

[0050]³/ 2.0 denier×3 inches

[0051]⁴/ 1.5 denier×3 inches

[0052]⁵/ 9 μm×2.5 inches

[0053] Poly (m-phenylene isophthalamide) staple fiber is commerciallyavailable as Nomex® from E. I. DuPont of Wilmington, Del., or as Conex®from Teijin Fiber Limited of New York, N.Y.; belCoTex® fiber isavailable from belChem Fiber Materials GmbH of Germany; poly(p-phenylene terephthalamide) staple fiber is available as Kevlar® fromE. I. DuPont of Wilmington, Del.; polybenzimidazole staple fiber isavailable as PBI® from Celanese Acetate of Charlotte, N.C.

Example 1

[0054] A first nonwoven felt batt is produced from fiber blend A havinga mass per unit area of from 11.0 to 12.0 oz/yd². A second nonwoven feltbatt is produced from fiber blend E having a weight of from 11.0 to 12.0oz/yd². The felt batts are then placed in intimate contact andmechanically needle punched according to methods well known by thoseskilled in the art to a needled weight of from 20.5 to 23.5 oz/yd² and aneedled thickness of from 0.575 to 0.725 inches.

[0055] A fluoropolymer treatment is then applied to the needled fabricas a means of imparting water repellency to the fabric. The treatmentconsists of 2.5% by volume Zonyl® RN, available from E. I. DuPont, and97.5% by volume water. Wet pickup is 100% based on the weight of thefabric. The treated fabric is then oven dried and cured at 450 to 475degrees Fahrenheit. The weight of the treated fabric is from 17.5 to21.5 oz/yd², and the thickness is from 0.500 to 0.650 inches. It may benoted that the fabric loses weight during the treatment anddrying/curing processes due to the effects of tension and stretching.The first and second batts produced from fiber blends A and E were thenpulled apart in order to insert an acoustic dampening layer.

[0056] A thermoplastic poly(vinylchloride) elastomer having a mass perunit area of about 12 to 15 oz/yd² and a thickness of approximately0.012 to 0.015 inches is positioned between the first and secondnonwoven batts. One example of such a material is Isodamp® C-1002available from E-A-R Specialty Composites of Indianapolis, Ind. Otherdampening materials may be used; for example, polyurethane, other foams,films, or elastomeric materials. The elastomeric dampening material wasadhered between the batts with a spray adhesive, available as Sta'-PutIV® Multipurpose Spray Adhesive SP4H from TACC International Corporationof Rockland, Mass. The finished insulating fabric had a weight of from24.3 to 29.7 oz/yd² and a thickness of from 0.625 to 0.825 inches. Itmay be noted that the finished insulating fabric loses weight, againfrom the effects of stretching the felt layers.

Example 2

[0057] A first nonwoven felt batt is produced from fiber blend A havinga mass per unit area of from 10.5 to 11.5 oz/yd². A second nonwoven feltbatt is produced from fiber blend E having a weight of from 10.5 to 11.5oz/yd². The felt batts are then placed in intimate contact andmechanically needle punched according to methods well known by thoseskilled in the art to a needled weight of from 20.5 to 23.5 oz/yd² and aneedled thickness of from 0.575 to 0.725 inches.

[0058] A fluoropolymer treatment is applied as in Example 1. Thefinished weight of the treated fabric is from 17.5 to 21.5 oz/yd², andthe finished thickness is from 0.500 to 0.650 inches.

Example 3

[0059] A first nonwoven felt batt is produced from fiber blend B havinga mass per unit area of from 11.6 to 12.8 oz/yd². A second and a thirdbatt are also produced having the same construction as said first batt.A fourth nonwoven felt batt is produced from fiber blend I having aweight of from 7.0 to 8.2 oz/yd². The three felt batts produced fromfiber blend B are then placed in intimate contact with the fourth feltbatt produced from fiber blend I positioned against the outermost faceof the three stacked batts of blend B. The four batts are thenmechanically needle punched according to methods well known by thoseskilled in the art to a needled weight of from 40.6 to 44.0 oz/yd² and aneedled thickness of from 1.125 to 1.500 inches.

[0060] A fluoropolymer treatment is applied as in Example 1. Thefinished weight of the treated fabric is from 35.1 to 42.9 oz/yd², andthe finished thickness is from 1.120 to 1.380 inches.

Example 4

[0061] A first nonwoven felt batt was produced from fiber blend C havinga mass per unit area of from 11.6 to 12.8 oz/yd². A second and a thirdbatt were also produced having the same construction as said first batt.A fourth nonwoven felt batt was produced from fiber blend B having aweight of from 7.0 to 8.2 oz/yd². The three felt batts produced fromfiber blend C were then placed in intimate contact, with the fourth feltbatt produced from fiber blend B positioned against the outermost faceof the three stacked batts of blend C. The four batts were thenmechanically needle punched according to methods well known by thoseskilled in the art to a needled weight of from 40.6 to 44.0 oz/yd² and aneedled thickness of from 1.125 to 1.500 inches.

[0062] A fluoropolymer treatment was applied as in Example 1. Thefinished weight of the treated fabric was from 35.1 to 42.9 oz/yd², andthe finished thickness was from 1.120 to 1.380 inches.

Example 5

[0063] This example was produced in the same manner as example 4, exceptfiber blend C was replaced with fiber blend D. All other conditionsincluding treatment and drying/curing remained the same for Example 5 asfor Example 4.

Example 6

[0064] This example was produced in the same manner as example 4, exceptfiber blend C was replaced with fiber blend E. All other conditionsincluding treatment and drying/curing remained the same for example 6 asfor example 4.

Example 7

[0065] This example was produced in the same manner as example 4, exceptfiber blend C was replaced with fiber blend F. All other conditionsincluding treatment and drying/curing remained the same for example 7 asfor example 4.

Example 8

[0066] A first nonwoven felt batt is produced from fiber blend D havinga mass per unit area of approximately 11.6 to 12.8 oz/yd². A second anda third batt are also produced having the same construction as saidfirst batt. A fourth nonwoven felt batt is produced from fiber blend Fhaving a weight of approximately 7.0 to 8.2 oz/yd². The three felt battsproduced from fiber blend D are placed in intimate contact, with thefourth felt batt produced from fiber blend F positioned against theoutermost face of the three stacked batts of blend D. The four batts arethen mechanically needle punched according to methods well known bythose skilled in the art to a needled weight of approximately 40.6 to44.0 oz/yd² and a needled thickness of about 1.125 to 1.500 inches.

[0067] A fluoropolymer treatment is applied as in Example 1. Thefinished weight of the treated fabric is from 35.1 to 42.9 oz/yd², andthe finished thickness is from 1.120 to 1.380 inches.

Example 9

[0068] This example is produced in the same manner as Example 1, exceptfiber blends A and E are replaced with fiber blend G. A treatment isapplied to impart hydrophobic character to the fibers and a sounddampening foam is used as in Example 1.

Example 10

[0069] A first nonwoven felt batt is produced from fiber blend H havinga mass per unit area of approximately 10.5 to 11.5 oz/yd². A secondnonwoven felt batt is produced having the same construction as the firstbatt. A scrim woven of 100% meta-aramid yam such as Conex® using a plainweave is used to support the fabric. The mass per unit area of the scrimis 2.1 oz/yd² with a construction of 22 ends per inch and 14 picks perinch. The felt batts are placed in intimate contact with one another andthe scrim is placed against an exterior face of the two batts. Theresulting composite is mechanically needle punched according to methodswell known by those skilled in the art to a needled weight ofapproximately 22.6 to 25.6 oz/yd² and a needled thickness ofapproximately 0.575 to 0.725 inches.

[0070] A fluoropolymer treatment is applied as in Example 1. Thefinished weight of the treated fabric is approximately 17.5 to 21.5oz/yd², and the finished thickness is approximately 0.500 to 0.650inches.

[0071] Preferred fabrics according to the invention exhibit reducedflame propagation. More specifically, a sample of a fabric according topreferred embodiments of the invention, when exposed to a radiant heatsource and a separate ignition source, shows no flaming beyond 2 inchesto the left of a centerline of a point of pilot flame application.Additionally, samples tested exhibited greatly improved performance inperformance in reducing the spread of flames on the surface of thematerial, and exhibited significantly shorter afterflames. Fabricsaccording to the invention when subjected to such ignition source for aperiod of 15 seconds, exhibit afterflame times of preferably less than 5seconds, more preferably less than 3 seconds, and most preferablyexhibit no afterflame at all.

[0072] Testing of material blends comprising 15% and 20% additions ofbelCoTex® fibers into standard meta-aramid (NOMEX®) fibers was conductedin accordance with the proposed changes to the Federal AviationAdministration's radiant panel test. The results of the testing areshown in FIG. 2 and FIG. 3, where the fiber composition and fabricthickness are as set forth in Table 2 below. Three iterations of thetest were performed on each sample, each of which is represented by aseparate bar on the bar graph. TABLE 2 Sample No. 1 2 3 4 5 6 7 Blend15% 15% 20% 20% 15% 20% 15% Belcotex ® Belcotex ® Belcotex ® Belcotex ®Belcotex ® Belcotex ® Belcotex ® 85% 85% 80% 80% 85% 80% 85% Nomex ®Nomex ® Nomex ® Nomex ® Nomex ® Nomex ® Nomex ® Thickness .187″ .4″.375″ .625″ .625″ .125″ .125″ After Flame Iteration 1 2 0 0.5 0 0 2.21.9 Iteration 2 1 0.5 0.5 0 0 2.8 10 Iteration 3 1.25 1 0 0.5 0 2.5 3Sample No. 8 9 10 11 12 13 Blend 20% 15% 20% 15% 20% 20% Belcotex ®Belcotex ® Belcotex ® Belcotex ® Belcotex ® Belcotex ® 80% 85% 80% 85%80% 80% Nomex ® Nomex ® Nomex ® Nomex ® Nomex ® Nomex ® Thickness .25″.25″ .5″ .5″ .25″ .2″ After Flame Iteration 1 0 1 0 0.75 1 1.5 Iteration2 0.5 1.5 1 0 0.5 0 Iteration 3 0 1 0 1.2 1 3

[0073] The data shows an improvement in performance over standardproducts that do not contain the inorganic fiber blend. All of thefabrics tested without addition of the modified silica fibers exhibitedsignificantly longer afterflame times when subjected to the radiantpanel test.

[0074] The foregoing examples and detailed description are not to bedeemed limiting of the invention which is defined by the followingclaims. The invention is understood to encompass such obviousmodifications thereof as would be apparent to those of ordinary skill inthe art.

What is claimed is:
 1. A fireblocking insulation material comprising atleast a first nonwoven batt having modified aluminum oxide-silica fiberspresent in an amount between about 1.0 percent by weight and 95.0percent by weight and organic fibers present in an amount between about5.0 percent by weight and about 99.0 percent by weight.
 2. Theinsulation material of claim 1 comprising a plurality of layers andincluding at least one further nonwoven batt comprising a blend oforganic fibers or a blend of organic fibers and inorganic fibers.
 3. Theinsulation material of claim 1 comprising a plurality of layers andincluding at least one layer which consists essentially of a blend oforganic fibers.
 4. The insulation material of claim 1, wherein at leastsaid first nonwoven batt is coated with a water resistant coating. 5.The insulation material of claim 3, wherein said water resistant coatingis a cured fluoropolymer coating.
 6. The insulation material of claim 1,wherein said modified aluminum oxide-silica fibers are acid-extracted.7. The insulation material of claim 6, wherein said modified aluminumoxide-silica fibers comprise about 70-75 percent by weight silica, 1-5percent by weight aluminum oxide and 15-25 percent by weight Na₂O. 8.The insulation material of claim 1 comprising a plurality of layers,more than one of said plurality of layers comprising a blend of organicfibers and modified aluminum oxide-silica fibers, and at least one ofsaid plurality of layers consisting essentially of organic fibers. 9.The insulation material of claim 1, said nonwoven batt having a weightper unit area between about 2.0 oz/yd² and about 15.0 oz/yd², and saidinsulation material having a weight per unit area between about 2.0oz/yd² and about 100.0 oz/yd², and said insulation material having athickness between about 0.05 to about 2.0 inches.
 10. The insulationmaterial of claim 2, said nonwoven batt having a weight per unit areabetween about 2.0 oz/yd² and about 15.0 oz/yd² and said insulationmaterial having a weight per unit area between about 20.0 and about 30.0oz/yd², and a thickness between about 0.05 inch and about 2.0 inch. 11.The insulation material of claim 2, said nonwoven batt having a weightper unit area between about 10.0 oz/yd² and about 15 oz/yd² and saidinsulation material having a weight per unit area between about 30.0 andabout 50.0 oz/yd² and a thickness between about 0.1 inch and about 2.0inch.
 12. The insulation material of claim 1, further comprising anacoustic dampening layer.
 13. The insulation material of claim 12,wherein said acoustic dampening layer comprises a layer ofpoly(vinylchloride), or polyurethane foam positioned between nonwovenlayers of the insulation material.
 14. The insulation material of claim2, further comprising at least one woven scrim supporting layer.
 15. Theinsulation material of claim 2, further comprising a water resistant andacoustic dampening facing film.
 16. The insulation material of claim 14,wherein said facing film is made from poly(vinylfluoride),poly(etheretherketone), polyimide, or fire retardant polyolefin andcovers at least one side of said insulation material.
 17. The insulationmaterial of claim 1, wherein said organic fibers comprise polym-phenylene isophthalamide fibers, poly p-phenylene terephthalamidefibers, polybenzimidazole fibers, or a mixture thereof.
 18. Theinsulation material of claim 1, exhibiting reduced flame propagation tomeet changes to the Federal Aviation Administration radiant panel testset forth in 14 C.F.R., Part 25, Appendix F thereof.
 19. The insulationmaterial of claim 1, exhibiting reduced flame propagation when exposedto a radiant heat source and a separate ignition source, such that whensaid ignition source is applied for a period of about 15 seconds, thefabric exhibits an afterflame of less than about 3 seconds.
 20. Afireblocking insulation material having a plurality of layerscomprising: a first nonwoven batt having a mass per unit area from about10.0 to about 15.0 oz/yd² and comprising about 15.0 to about 50.0percent by weight modified aluminum oxide-silica fibers having a meanfiber diameter of about 9 microns, and about 50.0 to about 85.0 percentby weight poly m-phenylene isophthalamide fibers, poly p-phenyleneterephthalamide fibers, polybenzimidazole fibers, or a mixture thereof,at least one additional nonwoven batt comprising organic fibers, saidfirst nonwoven batt and said at least one additional nonwoven battneedled together with an acoustic dampening layer and coated with awaterproof coating.
 21. The insulation material of claim 20, furthercomprising a poly(vinylfluoride), poly(etheretherketone) or polyimidefacing film forming the outer face of the insulation material.
 22. Theinsulation material of claim 21, further comprising a supporting scrim.23. A method of making an insulation material comprising: needlingtogether nonwoven batting layers, at least one of said batting layerscomprising modified aluminum oxide-silica fibers present in an amountbetween about 1.0 percent by weight and 95.0 percent by weight andorganic fibers present in an amount between about 5.0 percent by weightand about 99.0 percent by weight, coating the batting layers with acoating composition to effect water resistance, heating the coatedbatting layers to dry and cure the coating composition, adhering anelastomeric acoustic dampening layer to at least one of the battinglayers, and adhering or attaching a polymeric facing film.